This project is undertaken to examine the possibility that ingested antigens may play a role in the pathogenesis of immune complex disease. Antibodies to bovine gamma globulin were found more frequently in the sera of patients with systemic lumps erythematosus than in normal subjects, and in certain patients a circulating BGG-like material was found. In several patients both anti-BGG and the BGG-like material have been demonstrated supporting the possibility that antigenically intact molecules derived from ingested material may enter the circulation and participate in the formation of immune complexes. Preliminary studies have shown an increased incidence of anti-BGG in ulcerative colitis and chronic urticaria as well. In the coming year more sera from such patients and from other with chronic glomerulonephritis of unknown etiology will be examined for anti-BGG and circulating BGG. Tissues will be examined for the deposition of BGG:anti- BGG complexes. In addition, attempts to induce immune complex renal disease in nephritis prone mice by oral immunization with BGG will be continued. Studies on the possibility of the transmission of bovine proteins in human breast milk will also be carried out.